When a practitioner makes an impression of a patient's teeth and/or gums, he or she places a temporarily semi-fluid composition called an “impression material” into an impression tray and inserts the tray into the patient's mouth. The practitioner maneuvers the tray within the patient's mouth relative to the patient's teeth until the desired position of the tray with respect to the teeth is achieved. The tray is maintained in this position until the impression material hardens. After the impression material has hardened enough to retain its shape, the tray is then removed from the patient's mouth. The impression may be used for example in making models of teeth for reconstruction or replacement, or the impression may be used in any other situation where a dental impression is desired.
Prior impression trays would commonly need to be drilled to obtain a hole in the tray in various procedures. Drilling holes in a tray has several disadvantages, including the creation of small particles of material that may accidentally project into the practitioner's eyes, or may be inhaled by the patient or practitioner. Additionally, the particles may contaminate a sterile environment for example, during oral surgery. Drilling holes in a tray may deform the plastic due to heat generated during the drilling and causing the bur to stall. Further, drilling holes in a tray takes a good deal of time.
One prior tray may have sections removed. But if sections are removed from that tray, the overall size may be reduced and the tray is no longer suitable for taking an impression of an entire jaw. Further, such a tray is weak and not sufficiently strong or stable for taking a suitable impression or for maintaining the dimensional accuracy of the impression as the tray is being removed from a patient after the impression material hardens.